This invention relates to an internal combustion engine with a fuel injection system, and more particularly to an internal combustion engine with a fuel injection system wherein a fuel flow rate is controlled in accordance with an intake manifold pressure and an engine rotational speed.
Heretofore, the internal combustion engine (a so-called D-J engine) of the type described has been commonly operated at about the maximum output air-fuel ratio, i.e., on the side richer than the stoichiometric air fuel ratio, in consideration of the driveability. However, when a three-way catalyst is used to meet the engine exhaust gas control regulations, the purification factor of the three-way catalyst for contents in the exhaust gas including NO.sub.x, CO and HC can be high only when an air-fuel ratio is within a small region in a visinity of a stoichiometric air-fuel ratio. Therefore, in order to utilize the purification factor to the maximum, it is necessary to operate the engine at the stoichiometric air-fuel ratio.
In the D-J engine, the intake air-flow rate is determined in accordance with the intake manifold pressure and the engine rotational speed so that fuel commensurate to the intake air flow rate is injected to obtain a predetermined air-fuel ratio. With the D-J engine as described above, it has been known that, as for the air-fuel ratio during transitional condition such as acceleration and deceleration, the air-fuel ratio during acceleration becomes lean, and conversely, that during deceleration becomes rich. Accordingly, both the exhaust gas control and the driveability are not satisfactorily attained because of such phenomena in the air-fuel ratio during the transitional conditions.